<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var sum = 0;
        for(var i = 1 ; i <= 100; i++){
             sum += i;
        }
        document.writeln("1~100的累加和为：", sum);
    </script>
</body>
</html>